1. Field
Embodiments described herein generally relate to apparatus and processes for at least partially saturating and purifying syngas.
2. Description of the Related Art
Coal gasification is a high-temperature process usually conducted at elevated pressure to convert carbon-containing materials into carbon monoxide and hydrogen gas, commonly called “syngas.” The coal gasification process creates slag and ash in addition to the syngas. Additionally, the syngas can include byproducts such as tar and other hydrocarbons, ammonia, halides, and sulfur-containing compounds. Syngas can be further treated to produce a variety of desirable intermediate and end use products. For example, syngas can be reacted in a Fischer-Tropsch reactor to provide alkanes, or syngas can be reacted in a water-gas shift reactor to produce additional hydrogen. It is desirable, however, to remove ash and other particulates as well as any undesirable byproducts from the syngas before such downstream processes.
Gasification processes typically use one of two methods to remove slag and ash downstream from the gasifier. In a first process, slag and ash are removed as part of a water quench step. In a second process, slag and ash are removed from the hot gas stream exiting the gasifier by mechanical filtration and the syngas is later cooled in a separate step. While this second process removes a substantial amount of ash and particulate materials, small quantities still remain in the syngas, along with byproducts such as heavy and light hydrocarbons (C2-C20+), ammonia-containing compounds, sulfur-containing compounds, and halides.
There is a need, therefore, for improved apparatus and processes for removing ash and/or byproducts from syngas, while also at least partially saturating the syngas so that it may be used in downstream processes.